Fluid operated testing machines



F. CfHUYSER FLUID OPERATED TESTING MACHINES Filed Dec. 23, 1954 2Sheets-Sheet 1 w mun INVENTOR Evan/c4: Obi/n5 BY m mzm ATTO R N EY July15, 1958 F. c. HUYSER FLUID OPERATED TESTING MACHINES Filed Dec. 23,1954 2 Sheets-Sheet 2 Aw Q 31 25 27 I F mvus gag 124 /4 K BY Xlw/MQnxPWATTORNEYS 2,843,390 Patented July 15, 1958 fitice FLUID OPERATED TESTINGMACHINES Francis C. Huyser, Moline, Ill., assignor to American Machineand Metals, Inc., New York, N. Y., a corporation of Delaware Thisinvention relates to grips or chucks for specimen testing machines andparticularly to power operated grip means for use in torsion testingmachines and the like.

One of the problems in testing machines wherein a test specimen istwisted about its longitudinal axis is to grip the specimen so that itwill be held firmly from turning in the grip regardless of direction oftorque or dwell in movement thereof. Many prior gripping devices havebeen mechanically operated which do not provide sufficient grippingforce, and some have had a wedgeshaped arrangement so that the deviceswill tighten when force is exerted on the piece in one direction, buttend to loosen when force is in the other direction.

One of the objects of this invention is to provide a grip or chuckcapable of exerting high holding force between its specimen holdingmembers, said force not being affected by the direction in which thetorque is exerted on the specimen by the head or grip.

In one aspect of the invention, the gripping head may have jaw meansmovable inwardly relative to each other or toward a specimen, and mayhave fluid pressure motor means connected therewith for completing thetightening movement of the jaw means relative to said specimen.Sufiicient force can be exerted by a fluid motor to an extent notpossible with mechanical moving mechanisms, which insures that the jawmeans will grip the specimen with sufficient force to hold the same.Position locking means, such as a means movable between said jaw meansand the head, can be provided to lock or locate the jaw means in tightspecimen gripping position after operation of the pressure motor means.

In a preferred form, position locking nuts are screw threadedly mountedon the jaw means or means connecting the motor means and said jaw means,the nuts cooperating with an abutting face means on the head. The nutsmay have teeth on their exterior engageable by teeth located upon ashaft means, or by gear means so that when the shaft means is turned,the nuts will be appropriately rotated to lock the jaw means inposition. The nuts can be rotated to bring the jaw means initially intocontact with the specimen, such serving to properly synchronize thejaws. Fluid pressure then can be applied to the motor means to providethe required force to engage properly the specimen. The nuts then can beturned further to lock the jaw means in tight specimen gri pingposition. The nut means also could be mounted on the head and the fixedabutment carried by the jaw means or means moving the same. It isparticularly of importance that the jaw means engage the specimen in atorsion testing machine with suflicient force to prevent slippage of thespecimen as torque is applied thereto.

Other objects, features and advantages of this invention will beapparent from the following detailed description and the accompanyingdrawings of illustrative embodiments of the invention, which are merelyexemplary.

In the drawings:

Fig. 1 is a side elevational view of a torsion testing machine in whichthe grip means can be employed;

Fig. 2 is an enlarged front view of one of the gripping heads;

Fig. 3 is a cross section along line 3--3 of Fig. 2;

Fig. 4 is a cross section along line 4-4 of Fig. 2; and

Fig. 5 is an enlarged fragmentary front view of a portion of the grip,partly in section.

An example of one use of the invention is seen in Fig. 1 wherein atorsion testing machine can have gripping heads 11 and 12 for grippingtest specimen 13, it being understood that the invention is capable ofbeing used in other types of machines of this general nature, and is notlimited to a torsion testing machine.

In the illustrated torsion testing machine, gripping head 11 isrotatably mounted upon indicating unit 14, said unit having the usualindicating dial 15 together with a conventional stress-strain recordingunit if desired. Gripping head 11 can be arranged to transmit the loadexerted upon the specimen through a knife-edged lever system to apendulum load indicator, the applied load being automatically balancedagainst the corresponding displacement of a weighted pendulum.Indicating unit 14 can be moved along track means 16 so that specimensof different lengths can be accommodated between the gripping heads. Itshould be evident that either head could be so constructed as to bemoved .relative to the other and to the base of the machine.

Twisting head 12 can be carried upon the loading unit 17 and turned byany suitable mechanism such as a positive infinitely variable speeddrive.

Each of the gripping heads may have jaws 18 and 19 (Figs. 2, 3, 5)movable toward each other so as to grip a test specimen therebetween,said jaws preferably being V-shaped so as to grip a specimen on eitherside of a radial center line through the bottom of the notch of thejaws. Cylindrical members 20 and 21, carrying the jaw moving mechanism,are mounted in opposed relationship upon base member 22, fluidconnections 32, 33 being provided for cylindrical members 20, 21,respectively. A suitable fluid pressure supply system can. be connectedto pipes 32, 33, and by way of example, 50 to 60 tons of pressure orforce can be employed.

The details of the jaw actuating mechanism for jaw 19 will be described,jaw 18 also having a similar arrangement, identical numerals being usedwhere appropriate. Jaw 19 is movable inwardly and preferably radially bysubjecting piston 28 (Figs. 3 and 5) to fluid pressure, through pipeconnection 33, the force being exerted through shank 23 and jaw holder24 to the jaw. Jaw holder 24 has jaw retaining plates 25 fastened to theholder 24- by screws 26. The jaw holders are held in a recess in thehead and guided in their movement by guide plates 27. In the form shown,piston 28, shank 23 and jaw holder 24 are separable, projections 29 and30 being receivable in suitable apertures in the adjacent parts. Thepiston 28, shank 23 and jaw holder 24, of course, can be of unitaryconstruction. Packing 34 can be located between piston element 28 andshank 23, an O-ring or suitable packing 35 being located in a groove insaid shank.

Guide bushing 36 can be removably secured to the open end of cylindricalmember 21, said bushing serving as a stop face or abutment foradjustable position locking nut or means 37. Position locking nut 3'7has internal threads engaging threads 38 on shank 23.

Position locking nut operating shaft 39 is rotatably mounted in a bore40 in base 22, there being suitable bearings and means therein forlocating and holding said shaft. Shaft 39 has elongated gear teeth 41thereon extending axially a suflicient distance to provide for therequired travel of locking nuts 37 therealong. Turning of shaft 39 inthe proper direction by rotating projecting squared shank 42 thereofwill appropriately rotate nuts 3 37 and cause jaws 18 and 19 to movetoward each other, guide bushing 36 receiving the thrust exerted by thenuts.

As an example of operation of the device, a specimen to be tested can beinserted between jaws 18, 19 and shaft 39 is rotated until the rotationof the nuts causes the jaws 18 and 19 to contact the specimen. Fluidpressure then can be exerted through connections 32 and 33 on therespective opposing pistons to force the jaws into tight engagement withthe specimen. This will result in the nuts 37 moving inwardly andbecoming spaced from their respective bushings 36. Shaft 39 then isrotated further to bring the position locking nuts tightly against thefaces of their respective bushings 36 to lock or positively position thejaws in their tight specimen gripping condition. Thus, it is seen thatthe proper bite on the specimen is obtained hydraulically and that theparts then are locked with the jaws in their extended or specimengripping condition.

It is to be understood that the arrangement herein can be used for otherpurposes and that details ofconstruction can be varied without departingfrom the spirit of the invention exceptas defined in the appendedclaims.

What is claimed is:

1. In an article gripping device, the combination including jaw meansmovable radially on a base to engage an article, power operated meansconnected to said jaw means for exerting a large force on said jaw meansto tightly engage the article, and movable position locking meansbetween said jaw means and base, operable to lock said jaw means againstmovement in releasing direction when said jaw means is extended andtightly engaging the article.

2. In a testing machine specimen gripping device, the combinationincluding a gripping head, a pair of jaw means movable relatively towardand away from each other on said head, power operated means connected toeach jaw means, position locking means adjustably mounted between eachof said jaw means and said head, and means moving said locking means tohold said jaw means in the inwardly extended specimen holding positionwhen said jaw means have been so moved by said power operated means.

3. In a testing machine specimen gripping device, the combinationincluding a gripping head, a pair of jaw means movable relatively towardand away from each other on said head, power operated means connected toeach jaw means, position locking means adjustably mounted between eachof said jaw means and said head, said position locking means beingarranged to move said '4 jaw means toward each other to efiect aninitial gripping of a specimen, said power operated means beingeffective to move said jaws means into a final tightened position inwhich said specimen is held with great force, and means to move saidposition locking means so as to hold said jaw means in said finaltightened position.

4. A gripping head arrangement for. use in a testing machine or the likecomprising a pair of pressure cylinders mounted in aligned relationshipupon a gripping head, the end of each cylinder remote from the othercylinder being connected to a source of pressure, a slidably movablemember in each of said cylinders, each of said members having a threadedexterior portion, a jaw carried by each of said members, each memberbeing so movable that its respective jaw can be moved into specimengripping relationship with the jaw of the other member, and a positionlocking means threadedly mounted on the threaded exterior portionof eachmember, said jaws being movable by pressure in said cylinders so as totightly grip a specimen to be tested, said position locking means beingoperable to locate positively said members with respect to said'cylinders and to hold said specimen in said tightly gripped position.

5. A gripping head arrangement for use in a testing machine or the likecomprising a pair of pressure cylinders mounted in aligned relationshipupon a gripping head, the end of each cylinder remote from the othercylinder being connected to' a source of pressure, a slidably movablemember in each. of said cylinders, each of said members having athreaded exterior portion, a jaw carried by each of said members, eachmember being so movable that its respective: jaw can be moved intospecimen gripping relationship with. the jawof the other member, and aposition lockingmeans threadedly mounted on the threaded exteriorportionof each member, said means being arranged to move said jawstoward each other to eifect an initial grippingof'a specimen, said' jawsbeing movable by pressurein said cylindersso' as to hold the specimen ina final tightened positiongsaid position locking means being operable tolocate positively said members with respect tossaid cylinders and tohold said specimen in said final tightened position.

References Cited in the file of this patent UNITED STATES PATENTS2,345,401 Lindegren Mar; 28, 1944 2,587,893 Pridy et al Mar. 4, 19522,656,748 Hugo et al Oct. 27, 1953' 2,660,440 Kurtz Nov. 24, 19532,681,581 Pearson June 22, 1954

